Would like to know about the MTTR time calculations in case of reopened tickets.

We have monthly export listing various fields including Incident open time and resolution time. In case of tickets which are opened at time stamp , marked at time stamp B , reopened at C and finally resolved at D.

it gives incorrect in correct pictures when reports talks about Open (A) and final resolution time(D). Question is more from tools capabilities perspective , but would like to know how it is managed.

Why are you re-opening incident tickets? Very dangerous except where closure was some kind of "clerical" error, and in those cases the A to D is correct.

If you are including multiple incidents in one "Incident" then your figures are going to be wrong anyway._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718